Conventional flashlights require big and heavy batteries in order to achieve a level of luminosity and operating time, and therefore are large in outside dimensions as well as inconvenient when carrying. Further, it is difficult to detachably mount these flashlights onto other structures.
In recent years, very small, highly luminous LEDs were developed. These highly luminous LEDs enable to drastically reduce the size of light emitting portion of the flashlights. Another recent development has made available small, thin, platy batteries. However, in order to use a light emitting body at a high luminosity and to achieve a long operating time, it is still necessary to use a battery bigger than the light emitting body.
Another problem lies in that the flashlight needs a switch mechanism and an electric circuit for the light to turn on and off. If a portable flashlight is designed to be small, the conventional switch mechanism and the electric circuit are undesirably larger than the light emitting body.
Further, users occasionally want to attach their flashlights tentatively on their finger or on a structure for convenience. However, conventional fitting mechanisms are larger than the light emitting body or the batteries, and have complicated structures. Further, the fittings are only to fit specific objects, and do not allow flexible use on other objects. Therefore, it is difficult to use conventional flashlights in two ways, i.e. as an ordinary portable flashlight in one way, and as an electric torch attachable to other structures in the other way.